Men who have sex with men

Men who have sex with men (MSM) are men who engage in sexual activity with other men, regardless of their sexual orientation or sexual identity. The term was created by epidemiologists in the 1990s, to better study and communicate the spread of sexually transmitted infections such as HIV/AIDS between all sexually active males, not strictly those identifying as gay, bisexual, pansexual or various other sexualities, but also for example male prostitutes.

Source: Wikipedia — Men who have sex with men (CC BY-SA 4.0)